Solved: Two metals, A and B, form a substitutional alloy

Problem 33E Referring to Table 23.2 , explain why you might expect Cr and Fe to form miscible alloys.

Problem 34E Referring to Table 23.2 , explain why you might expect Co and Cu to not form miscible alloys.

Problem 35E Determine the composition and phases present at points A and B on the Cr-Fe phase diagram.

Problem 36E Determine the composition and phase present at points C and D on the Cr-Fe phase diagram (see previous problem for diagram).

Problem 37E Determine the composition, relative amounts, and phases present at points A and B on the Co-Cu phase diagram.

Problem 38E Determine the composition, relative amounts and phases present at points C and D on the Co-Cu phase diagram (see previous problem for phase diagram).

Problem 39E The elements Mn and Si are added to steel to improve its properties in electric motors, and some C is often found as a detrimental impurity. Which of these elements fills interstitial holes in the Fe lattice and which substitutes for the Fe in the lattice?

Problem 40E The elements Si and P are added to steel to improve its properties in electric motors, and some N is often found as a detrimental impurity. Which of these elements fills interstitial holes in the Fe lattice and which substitutes for the Fe in the lattice?

Problem 41E Determine the formula for each interstitial alloy. a. Nitrogen occupies one-half of the octahedral sites of a closest-packed Mo structure. b. Hydrogen occupies all of the tetrahedral sites of a Cr closest-packed structure.

Problem 42E Determine the formula for each interstitial alloy. a. Nitrogen occupies one-fourth of the octahedral sites of a closest-packed Fe structure. b. Hydrogen occupies one-half of the tetrahedral sites of a Ti closest-packed structure.

Problem 43E Identify the metal found in each mineral. a. sphalerite b. malachite c. hausmannite

Problem 44E Name at least one important mineral that is a source for each metal. a. Fe b. Co c. Cr

Problem 45E Calculate the heat of reaction for rhodochrosite is - 894.1 kJ/mol.)

Problem 46E The extraction of Mn from pyrolusite with aluminum produces pure Mn metal and AI203 . Calculate the heat of reaction

Problem 47E Describe the effects of adding Cr to steel and give a use for chromium-steel alloys.

Problem 48E Describe the effects of adding Mn to steel and give a use for manganese-steel alloys.

Problem 49E Calculate the mole percent and mass percent of Ti in the minerals rutile and ilmenite Formulas:

Problem 50E Calculate the mole percent and mass percent of Mn in the minerals pyrolusite and rhodochrosite.

Problem 51E Why is it important to use an inert atmosphere to surround the metal when arc-melting titanium?

Problem 52E Titanium is a very reactive metal. Explain why titanium has a high corrosion resistance to seawater and can be used for the production of ship components.

Problem 53E Which compound of Ti is the most important industrial product of titanium metal? Describe an application for this compound.

Problem 54E Describe how Zn is used to protect the surface of steel products. What is the name of this process?

Problem 55E Describe the Bayer process.

Problem 56E Describe the Mond process.

Problem 57E Which metals are found in carbaloy steel?

Problem 58E Which metals are found in Monel steel?

Problem 59E After 2.0 x 104 kg of an ore that contains 0.051% ilmenite is mined, the percent yield from extracting and refining the metals from the mineral is 87% for the iron and 63% for the titanium. Calculate the mass of iron and titanium produced from the ore.

Problem 60E Calculate the mass of aluminum metal that is needed to produce Cr metal from 5.00 x0 102 g of chromite. Calculate how many grams of Cr rnetal are produced from 5.00 x 102 g of chromite.

Problem 61E How many lattice atoms surround a tetrahedral hole and an octahedral hole in a closest-packed structure? Describe which hole site is larger and explain why.

Problem 64E Why is Mn02 added to silica glass?

Problem 63E Why does Mn form compounds with higher oxidation states than Cr?

Problem 62E Explain why the crystal structure and atomic size of the two elements are important factors in a two-component phase diagram.

Why does chromium seem to be less reactive than its standard reduction potential suggests?

Define the following terms: coordination compound, ligand, donor atom, coordination number, chelating agent

Describe the interaction between a donor atom and a metal atom in terms of a Lewis acid-base reaction.

Complete the following statements for the complex ion [Co(en)2(H2O)CN]21. (a) en is the abbreviation for . (b) The oxidation number of Co is . (c) The coordination number of Co is . (d) is a bidentate ligand.

Complete the following statements for the complex ion [Cr(C2O4)2(H2O)2] 2. (a) The oxidation number of Cr is . (b) The coordination number of Cr is . (c) is a bidentate ligand.

Give the oxidation numbers of the metals in the following species: (a) K3[Fe(CN)6], (b) K3[Cr(C2O4)3], (c) [Ni(CN)4] 22.

Give the oxidation numbers of the metals in the following species: (a) Na2MoO4, (b) MgWO4, (c) Fe(CO)5.

What are the systematic names for the following ions and compounds? (a) [Co(NH3)4Cl2] 1 (c) [Co(en)2Br2] 1 (b) Cr(NH3)3Cl3 (d) [Co(NH3)6]Cl3

What are the systematic names for the following ion and compounds? (a) [cis-Co(en)2Cl2] 1 (b) [Pt(NH3)5Cl]Cl3 (c) [Co(NH3)5Cl]Cl2

Write the formulas for each of the following ions and compounds: (a) tetrahydroxozincate(II), (b) pentaaquachlorochromium(III) chloride, (c) tetrabromocuprate(II), (d) ethylenediaminetetraacetat oferrate(II).

Write the formulas for each of the following ions and compounds: (a) bis(ethylenediamine)- dichlorochromium(III), (b) pentacarbonyliron(0), (c) potassium tetracyanocuprate(II), (d) tetraammineaquachlorocobalt(III) chloride.

Define the following terms: stereoisomers, geometric isomers, optical isomers, plane-polarized light

Specify which of the following structures can exhibit geometric isomerism: (a) linear, (b) square- planar, (c) tetrahedral, (d) octahedral.

What determines whether a molecule is chiral? How does a polarimeter measure the chirality of a molecule?

Explain the following terms: (a) enantiomers, (b) racemic mixtures.

The complex ion [Ni(CN)2Br2] 22 has a square-planar geometry. Draw the structures of the geometric isomers of this complex.

How many geometric isomers are in the following species? (a) [Co(NH3)2Cl4] 2, (b) [Co(NH3)3Cl3]

Draw structures of all the geometric and optical isomers of each of the following cobalt complexes: (a) [Co(NH3)6] 31 (b) [Co(NH3)5Cl]21 (c) [Co(C2O4)3] 32

Draw structures of all the geometric and optical isomers of each of the following cobalt complexes: (a) [Co(NH3)4Cl2] 1, (b) [Co(en)3] 31

Briefly describe crystal field theory

Define the following terms: crystal field splitting, high-spin complex, low-spin complex, spectrochemical series.

What is the origin of color in a coordination compound?

Compounds containing the Sc31 ion are colorless, whereas those containing the Ti31 ion are colored. Explain.

What factors determine whether a given complex will be diamagnetic or paramagnetic?

For the same type of ligands, explain why the crystal field splitting for an octahedral complex is always greater than that for a tetrahedral complex.

The [Ni(CN)4] 22 ion, which has a square-planar geometry, is diamagnetic, whereas the [NiCl4] 22 ion, which has a tetrahedral geometry, is paramagnetic. Show the crystal field splitting diagrams for those two complexes.

Transition metal complexes containing CN2 ligands are often yellow in color, whereas those containing H2O ligands are often green or blue. Explain.

Predict the number of unpaired electrons in the following complex ions: (a) [Cr(CN)6] 42, (b) [Cr(H2O)6] 21.

The absorption maximum for the complex ion [Co(NH3)6] 31 occurs at 470 nm. (a) Predict the color of the complex and (b) calculate the crystal field splitting in kJ/mol.

From each of the following pairs, choose the complex that absorbs light at a longer wavelength: (a) [Co(NH3)6] 21, [Co(H2O)6] 21; (b) [FeF6] 32, [Fe(CN)6] 32; (c) [Cu(NH3)4] 21, [CuCl4] 22.

A solution made by dissolving 0.875 g of Co(NH3)4Cl3 in 25.0 g of water freezes at 20.568C. Calculate the number of moles of ions produced when 1 mole of Co(NH3)4Cl3 is dissolved in water and suggest a structure for the complex ion present in this compound.

Define the terms (a) labile complex, (b) inert complex

Explain why a thermodynamically stable species may be chemically reactive and a thermodynamically unstable species may be unreactive.

Oxalic acid, H2C2O4, is sometimes used to clean rust stains from sinks and bathtubs. Explain the chemistry underlying this cleaning action

The [Fe(CN)6] 32 complex is more labile than the [Fe(CN)6] 42 complex. Suggest an experiment that would prove that [Fe(CN)6] 32 is a labile complex.

Aqueous copper(II) sulfate solution is blue in color. When aqueous potassium fluoride is added, a green precipitate is formed. When aqueous potassium chloride is added instead, a bright-green solution is formed. Explain what is happening in these two cases.

When aqueous potassium cyanide is added to a solution of copper(II) sulfate, a white precipitate, soluble in an excess of potassium cyanide, is formed. No precipitate is formed when hydrogen sulfide is bubbled through the solution at this point. Explain.

A concentrated aqueous copper(II) chloride solution is bright green in color. When diluted with water, the solution becomes light blue. Explain.

In a dilute nitric acid solution, Fe31 reacts with thiocyanate ion (SCN2) to form a dark-red complex: [Fe(H2O)6] 31 1 SCN2 H2O 1 [Fe(H2O)5NCS]21 The equilibrium concentration of [Fe(H2O)5NCS]21 may be determined by how darkly colored the solution is (measured by a spectrometer). In one such experiment, 1.0 mL of 0.20 M Fe(NO3)3 was mixed with 1.0 mL of 1.0 3 1023 M KSCN and 8.0 mL of dilute HNO3. The color of the solution quantitatively indicated that the [Fe(H2O)5NCS]21 concentration was 7.3 3 1025 M. Calculate the formation constant for [Fe(H2O)5NCS]21.

As we read across the first-row transition metals from left to right, the 12 oxidation state becomes more stable in comparison with the 13 state. Why is this so?

Which is a stronger oxidizing agent in aqueous solution, Mn31 or Cr31? Explain your choice.

Carbon monoxide binds to Fe in hemoglobin some 200 times more strongly than oxygen. This is the reason why CO is a toxic substance. The metal-toligand sigma bond is formed by donating a lone pair from the donor atom to an empty sp3 d2 orbital on Fe. (a) On the basis of electronegativities, would you expect the C or O atom to form the bond to Fe? (b) Draw a diagram illustrating the overlap of the orbitals involved in the bonding

What are the oxidation states of Fe and Ti in the ore ilmenite, FeTiO3? (Hint: Look up the ionization energies of Fe and Ti in Table 23.1; the fourth ionization energy of Ti is 4180 kJ/mol.)

A student has prepared a cobalt complex that has one of the following three structures: [Co(NH3)6]Cl3, [Co(NH3)5Cl]Cl2, or [Co(NH3)4Cl2]Cl. Explain how the student would distinguish between these possibilities by an electrical conductance experiment.At the students disposal are three strong electrolytesNaCl, MgCl2, and FeCl3which maybe used for comparison purposes

Chemical analysis shows that hemoglobin contains 0.34 percent of Fe by mass. What is the minimum possible molar mass of hemoglobin? The actual molar mass of hemoglobin is about 65,000 g. How do you account for the discrepancy between your minimum value and the actual value?

Explain the following facts: (a) Copper and iron have several oxidation states, whereas zinc has only one. (b) Copper and iron form colored ions, whereas zinc does not.

A student in 1895 prepared three coordination compounds containing chromium, with the following properties: Cl2 Ions in Solution per Formula Color Formula Unit (a) CrCl3 ? 6H2O Violet 3 (b) CrCl3 ? 6H2O Light green 2 (c) CrCl3 ? 6H2O Dark green 1 Write modern formulas for these compounds and suggest a method for confirming the number of Cl2 ions present in solution in each case. (Hint: Some of the compounds may exist as hydrates and Cr has a coordination number of 6 in all the compounds.)

The formation constant for the reaction Ag1 1 2NH3 [Ag(NH3)2] 1 is 1.5 3 107 and that for the reaction Ag1 1 2CN2 [Ag(CN)2] 2 is 1.0 3 1021 at 258C (see Table 16.3). Calculate the equilibrium constant and DG8 at 258C for the reaction [Ag(NH3)2] 1 1 2CN2 [Ag(CN)2] 2 1 2NH3

From the standard reduction potentials listed in Table 18.1 for Zn/Zn21 and Cu1/Cu21, calculate DG8 and the equilibrium constant for the reaction Zn(s) 1 2Cu21(aq) Zn21(aq) 1 2Cu1(aq)

Using the standard reduction potentials listed in Table 18.1 and the Handbook of Chemistry and Physics, show that the following reaction is favorable under standard-state conditions: 2Ag(s) 1 Pt21(aq) 2Ag1(aq) 1 Pt(s) What is the equilibrium constant of this reaction at 258C?

The Co21-porphyrin complex is more stable than the Fe21-porphyrin complex. Why, then, is iron the metal ion in hemoglobin (and other heme- containing proteins)?

What are the differences between geometric isomers and optical isomers?

Oxyhemoglobin is bright red, whereas deoxyhemoglobin is purple. Show that the difference in color can be accounted for qualitatively on the basis of high-spin and low-spin complexes. (Hint: O2 is a strong-field ligand; see the Chemistry in Action essay on p. 1016.)

Hydrated Mn21 ions are practically colorless (see Figure 23.20) even though they possess five 3d electrons. Explain. (Hint: Electronic transitions in which there is a change in the number of unpaired electrons do not occur readily.)

Which of the following hydrated cations are colorless: Fe21(aq), Zn21(aq), Cu1(aq), Cu21(aq), V51(aq), Ca21(aq), Co21(aq), Sc31(aq), Pb21(aq)? Explain your choice.

Aqueous solutions of CoCl2 are generally either light pink or blue. Low concentrations and low temperatures favor the pink form while high concentrations and high temperatures favor the blue form. Adding hydrochloric acid to a pink solution of CoCl2 causes the solution to turn blue; the pink color is restored by the addition of HgCl2. Account for these observations.

Suggest a method that would allow you to distinguish between cis-Pt(NH3)2Cl2 and trans- Pt(NH3)2Cl2.

You are given two solutions containing FeCl2 and FeCl3 at the same concentration. One solution is light yellow and the other one is brown. Identify these solutions based only on color.

The label of a certain brand of mayonnaise lists EDTA as a food preservative. How does EDTA prevent the spoilage of mayonnaise?

The compound 1,1,1-trifluoroacetylacetone (tfa) is a bidentate ligand: O B O B CF3CCH2CCH3 It forms a tetrahedral complex with Be21 and a square planar complex with Cu21. Draw structures of these complex ions and identify the type of isomerism exhibited by these ions

How many geometric isomers can the following square planar complex have? a b G D Pt D G d c

[Pt(NH3)2Cl2] is found to exist in two geometric isomers designated I and II, which react with oxalic acid as follows: I 1 H2C2O4 [Pt(NH3)2C2O4] II 1 H2C2O4 [Pt(NH3)2(HC2O4)2] Comment on the structures of I and II.

The Kf for the complex ion formation between Pb21 and EDTA42 Pb21 1 EDTA42 Pb(EDTA)22 is 1.0 3 1018 at 258C. Calculate [Pb21] at equilibrium in a solution containing 1.0 3 1023 M Pb21 and 2.0 3 1023 M EDTA42.

Manganese forms three low-spin complex ions with the cyanide ion with the formulas [Mn(CN)6] 52, [Mn(CN)6] 42, and [Mn(CN)6] 32. For each complex ion, determine the oxidation number of Mn and the number of unpaired d electrons present.

Commercial silver-plating operations frequently use a solution containing the complex Ag(CN)2 2 ion. Because the formation constant (Kf) is quite large, this procedure ensures that the free Ag1 concentration in solution is low for uniform electrodeposition. In one process, a chemist added 9.0 L of 5.0 M NaCN to 90.0 L of 0.20 M AgNO3. Calculate the concentration of free Ag1 ions at equilibrium. See Table 16.4 for Kf value.

Draw qualitative diagrams for the crystal field splittings in (a) a linear complex ion ML2, (b) a trigonalplanar complex ion ML3, and (c) a trigonal-bipyramidal complex ion ML5.

(a) The free Cu(I) ion is unstable in solution and has a tendency to disproportionate: 2Cu1(aq2 Cu21(aq) 1 Cu(s) Use the information in Table 18.1 (p. 821) to calculate the equilibrium constant for the reaction. (b) Based on your result in (a), explain why most Cu(I) compounds are insoluble.

Consider the following two ligand exchange reactions: [Co(H2O)6] 31 1 6NH3 [Co(NH3)6] 31 1 6H2O [Co(H2O)6] 31 1 3en [Co(en)3] 31 1 6H2O (a) Which of the reactions should have a larger DS8? (b) Given that the CoN bond strength is approximately the same in both complexes, which reaction will have a larger equilibrium constant? Explain your choices.

Copper is also known to exist in the 13 oxidation state, which is believed to be involved in some biological electron-transfer reactions. (a) Would you expect this oxidation state of copper to be stable? Explain. (b) Name the compound K3CuF6 and predict the geometry of the complex ion and its magnetic properties. (c) Most of the known Cu(III) compounds have square planar geometry. Are these compounds diamagnetic or paramagnetic?

Problem 1E Why is vanadium present in oil from some sources?

Problem 1SAQ Which metal is naturally found in its elemental state? a) gold b) titanium c) chromium d) iron

Problem 2E List three categories of metallurgical processes.

Problem 2SAQ Which reaction is an example of pyrometallurgy?

Problem 3E Why is Ni not considered a common metal even though it composes over 2% of the total mass of Earth and only Fe and Mg have a higher percent composition of Earth's total mass?

Problem 3SAQ Based on the data in the table, which pair of metals is likely to form a substitutional alloy?

Problem 4E Metal elements are found in both minerals and ores. Describe the difference between a mineral and an ore.

Problem 4SAQ Two metals, A and B, form a substitutional alloy with the binary phase diagram shown here. What is the melting point of the alloy at a composition that is 75% A and 25% B? a) 1000 oC b) 1300 oC c) 1450 oC d) 2000 oC

Problem 5E Ores contain minerals and gangue. Describe the difference between a mineral and gangue.

Two metals, A and B, form a substitutional alloy with the binary phase diagram shown here. Determine the composition and relative amounts of the two phases present at 50% composition and \(1500 \ ^\circ C\). a) The A-rich bcc phase is 80% A and 20% B; the B-rich fee phase is 37% A and 63% B; the mixture contains more of the A-rich fee phase. b) The A-rich bcc phase is 20% A and 80% B; the B-rich fee phase is 63% A and 37% B; the mixture contains more of the B-rich fee phase. c) The A-rich bcc phase is 50% A and 50% B; the B-rich fee phase is 50% A and 50% B; the mixture contains equal amounts of both phases. d) The A-rich bcc phase is 80% A and 20% B; the B-rich fee phase is 37% A and 63% B; the mixture contains more of the B-rich fee phase.

Problem 6E Calcination, roasting, and smelting are three pyrometallurgical processes. Compare and contrast the processes.

Problem 6SAQ An interstitial alloy contains a nonmetal (X) that occupies one-fourth of the octahedral holes in the closet-packed lattice of the metal (M). What is the formula for the alloy? a) M4X b) MX4 c) M2X d) MX2

Problem 7E What compound has been historically used to leach gold from gold ores? Why is this process being discontinued?

Which metal is commonly used to make electrical wires? a) zinc b) cobalt c) manganese d) copper

Problem 8E Name three advantages of making metal components from the powder metallurgical process.

Problem 8SAQ Which metal is commonly used to make parts for aircraft engines? a) zinc b) titanium c) nickel d) silver

Describe the difference between body-centered cubic and face centered cubic structures.

Problem 9SAQ Calculate the mass percent of chromium in the mineral chromite a) 33.97% b) 46.46% c) 36.73% d) 36.13%

Problem 10E Describe the difference between a substitutional alloy and an interstitial alloy.

Problem 10SAQ What is a common use for zinc? a) galvanization of steel b) lightweight aircraft parts c) paint pigments d) production of magnets

Problem 11E Why was copper one of the first metals that humans used?

Problem 12E Describe why bronze was one of the first alloys that humans used.

Both brass and bronze contain copper. Describe the difference between these two alloys.

Problem 14E List the properties of copper that make it appropriate for electric wires and the properties that make it appropriate for water pipes.

Describe three typical properties of metals.

Describe whether each property is generally higher or lower for metals compared to nonmetals. a. thermal conductivity b. electrical resistivity c. transparency d. ductility

List four metal elements that each individually compose more than 1% of Earth's crust.

Problem 19E List the name and formula of one important mineral source for each of these metals: Fe, Hg, V, and Nb.

Problem 18E List four metals that occur as elements in their natural state.

Problem 20E List the name and formula of one important mineral source for each of these metals: Ti. Zn, U, and Ta.

Problem 21E Two ores of magnesium are MgC03 and Mg(OH)2 . Write balanced equations for the calcination of these two minerals to form MgO.

Two ores of copper are CuO and CuS. Write balanced equations for the roasting of CuO with C to form Cu metal and the roasting of CuS with \(O_2\) to form CuO.

Problem 23E Give the definition of a flux and identify the flux in the reaction.

Problem 25E Provide a general description of how hydrometallurgy is used to extract metals from ores.

Problem 24E Give the definition of a slag and identify the slag in the reaction.

Problem 26E Provide a general description of how electrometallurgy is used to extract metals from ores.

Problem 28E When copper is purified using an electrochemical cell, which electrode has the pure copper and which electrode has the impure copper? Explain how gold is obtained from this process.

Problem 27E How is AI203 separated from other oxides using the Bayer process? What soluble form of aluminum forms from AI203 during the Bayer process?

Problem 29E Describe the difference between sponge powdered iron and water-atomized powdered iron.

Describe the difference in the processing of sponge powdered iron and water-atomized powdered iron.

Problem 31IE Determine the composition of each vanadium alloy. a. One-half of the V atoms are replaced by Cr atoms. b. One-fourth of the V atoms are replaced by Fe atoms. c. One-fourth of the V atoms are replaced by Cr atoms, and one-fourth of the V atoms are replaced by Fe atoms.

Problem 32E Determine the composition of each cobalt alloy. a. One-third of the Co atoms are replaced by Zn atoms. b. One-eighth of the Co atoms are replaced by Ti atoms. c. One-third of the Co atoms are replaced by Zn atoms, and one-sixth of the Co atoms are replaced by Ti atoms.

Co, Fe, and Ni are ferromagnetic. What is the difference between ferromagnetic and paramagnetic?

Problem 67E The first ionization energies of iron, cobalt, nickel, and the first three platinum metals are all about the same, but the first ionization energies of osmium, iridium, and platinum are substantially greater. Suggest an explanation for this observation.

Problem 66E Is the chromate ion or dichromate ion more stable in an acidic solution? Which ion has a higher Cr:0 ratio? Which ion has a higher oxidation state for Cr?

Although both the Group IA and IB metals have a half-filled s subshell, the IB metals have markedly higher first ionization energies, densities, and melting points, and markedly lower second and third ionization energies than the corresponding IA metals. Explain these observations.

Iron powder is placed into a tall cylinder-shaped die and pressed from the top and bottom to make a cylinder-shaped pressed part with a height of 5.62 cm and radius of 4.00 cm. The density of the iron powder before it was pressed was 2.41 g/mL. The density of a pressed iron part is 6.85 g/mL. The density of pure solid iron is 7.78 g/mL. a. Calculate the original height of the powder before it was pressed. b. Calculate the theoretical height of the pressed component if it could be pressed to the same density of pure iron. c. What percentage of the component is composed of voids between the iron particles?

Problem 70E When a part is made by pressing together powdered metal, no metal is wasted. In contrast, metal is typically scrapped after a metal part is cut from a solid metal plate. If a circular part with a diameter of 10.0 cm is made from an original shape of a square with a side length of 10.0 cm, calculate the percentage of the metal that is thrown away as scrap. If the circular shape also has a circular hole with a diameter of 6.0 cm, calculate the percentage of the metal that is thrown away as scrap.

Hydrogen can be in both the octahedral and tetrahedral holes for lanthanum. Determine the percentage of the holes that are filled if the formula is \(\mathrm{LaH}_{2.76}\).

Problem 72E Tin exists in two allotropic forms. Gray tin has a diamond structure and white tin has a close-packed structure. Predict which allotrope is (a) denser, (b) a conductor of electricity. Predict the valence electronic configuration of tin in each allotrope.

Problem 73E Find the equilibrium constant at 298 K for the reaction. The Kf for and the rest of the data needed are in Appendix II .

Find the equilibrium constant at 298 K for the reaction. \(2\ \left[\mathrm{Cu}\left(\mathrm{NH}_3\right)_2\right]^+(aq)\ \rightleftharpoons\ \left[\mathrm{Cu}\left(\mathrm{NH}_3\right)_4\right]^{2+}(aq)+\mathrm{Cu}(s)\) The \(K_{\mathrm{f}}\) for \(\left[\mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{2}\right]^{+}=6.3 \times 10^{10}\) and the rest of the data needed are in Appendix II.

Problem 75E Propose a chemical procedure to extract cobalt from the mineral cobaltite, . What are some of the hazards of such a procedure?

Why are metals such as Ni and Co economical to mine and use in industrial processes even though they have a very low natural abundance in Earth's crust?

Explain why metals such as Au and Ag are found in their elemental states in nature, but metals like Na and Ca are always found in compounds in nature.

Problem 78E What allows some pairs of metals to form alloys that have the same structure at any composition, while other pairs of metals form alloys with structures that depend on the relative composition of the two metals?